The present invention relates generally to a transmission control strategy and more particularly to a method and apparatus for controlling the fluid pressure of an inching clutch.
Transmissions on earth moving machines, such as track type tractors and motorgraders, have many different gear ratios that are each provided by engaging certain ones of a plurality of fluid actuated clutches. These clutches are normally engaged by directing pressurized fluid through respective pressure modulation valves that are likewise controlled by electronic clutch pressure control valves. The electronic clutch pressure control valves are controlled in response to receipt of an electrical signal received from a controller. Many times it is desirable to have a smooth transition from neutral to a gear, for example, when hitching up an implement in a confined space. However, in current systems, when the gears are changed there is a xe2x80x9cjerkxe2x80x9d when the appropriate clutch is engaged. The xe2x80x9cjerkxe2x80x9d is due to the inching clutch being filled to slowly or rapidly. The xe2x80x9cjerkxe2x80x9d leads to operator fatigue and transmission wear.
The present invention is directed to overcoming one or more of the problems set forth above.
In one aspect of the present invention, a method is provided for controlling the pressure of an actuating fluid associated with an inching clutch. The invention includes the steps of determining an actual pressure of the fluid, and responsively controlling the pressure.
In another aspect of the present invention an apparatus for controlling the pressure of an actuating fluid flowing through a valve and an inching clutch is disclosed. The apparatus includes a pressure sensing device adapted to sense an actual pressure of the actuating fluid and generate an a pressure signal and a controller adapted to receive the pressure signal, establish an inching pressure threshold, responsively control the pressure of the fluid.